www.MSruns.com read only forum (Jan.15,2018)

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Heres a load of info on my build. There are notes that can possibly help others looking to do something similar.

PHOTO GALLERY OF BUILD: https://www.dropbox.com/gallery/1013438 ... s?h=48b02f
*Note that the photos are out of order, and there was a period of time where the car was driving around with the turbo installed but not connected to the intake and still on the stock ecu. Hence you will see some pics with the stock intake airbox over the turbo. The stock ecu ran the ej20G without boost PERFECTLY. Plug&play. Also of note - this car was originally acquired with a small amount of front end damage, which also destroyed the stock engine (there are carnage photos in the gallery). the car shell was bought for $650 with a blown engine, and the build was done on a budget of about $4000. So total cost in this car is about $4600-4800. Although this is with many used parts, including a FREE turbo engine and a $40 transmission. With the tiny WRX turbo, it probably puts out about 250-270hp at the engine. with any decent turbo upgrade, this car could easily put out around 300 wheel horsepower or 360-380hp at the engine and still be reliable. i feel that engine internals should be upgraded past this point but no doubt others have had no trouble making more power and yet others have had failures on a stock engine so its really all luck of the draw and your attention to detail in the build and tuning process, and if you had a motor that was previously abused.

GM IAT and CLT sensors - these are 3/8 pipe thread i believe and fairly cheap. i picked them up at my local auto parts store as well as the wiring pigtails. there are generic part equivalents as well. i went this route with the coolant temp sensor instead of using the stock one. reason being i didnt feel like going through the trouble of calibrating the sensor. the gm sensor was cheap enough, calibration for it is built into the MS, and it took all of about 10 minutes to drill and tap the old stock sensor's hole out to 3/8 thread. also the intake air temp sensor was required for speed density. i drilled and tapped right into the top of the intake manifold and mounted it there.

Wiring harness - I wanted to hack up the car as little as possible, since i have been horrified at seeing swaps done with hacked up harnesses and wires joined by loosely twisting bare wires together and leaving them uncovered. yeah - some people should not work on cars!!!! so i decided to do everything as proper and reversible and clean as possible. i created what i have heard some call a "boomslang" harness. probably because the company that goes by that name makes ecu adapter harnesses. i destroyed the stock ecu to get at its big one-piece connector socket. i then used the DIYautotune TXL wires and some solder and a whole lot of shrink wrap tubing to mate the pins on the socket to the DB37 connectors. the factory harness in the compartment under the glovebox is untouched. it plugs right into the adapter harness which then plugs into the MS. however, the stock ecu still cannot be simply swapped in because certain modifications had to be made in the engine bay. in order to run the coilpacks and BCS and IAT sensor, new wires would have to be run. instead of do this, i chose to keep it clean. i made a few small and reversible adaptations to the engine bay harness. i repurposed some of the emissions related wires (o2 sensors, EGR, etc) for other functions. i also repurposed the wires from the ignitor and the maf sensor connector i believe.

02-05 USDM WRX coilpacks - these bolted right onto the EJ20G heads no problem. the MS controls them fine. note that the coilpacks that came on this 90's engine were COP as well, however they are "dumb" coils, meaning that they require a separate ignitor to function. the ms would not be able to control them directly, as they need an amplifier of sorts. i think usually the amp supplies about 400v or less to the coils, and the coils step it up to 10's of thousands of volts. the new-age USDM wrx/sti coilpacks have built-in ignitors and are "smart" coilpacks. they only require power, ground, and a 5v logic level signal to fire. the trick when setting these up at first is to get the setting correct for how to trigger the coils - going low or going high. in my setup, the coilpacks were all wired to the ignition fuse, and i knew right away that i had the setting reversed when i turned the ignition on - the ignition fuse popped immediately as all 4 coils were charging at the same time for much longer than they should be. after switching the setting in tunerstudio everything worked ok.

02-05 USDM WRX throttle body - this was an important part of the swap. the design of the idle control valve that came with the legacy was not the best choice for a boosted application. the single biggest issue was that it hung off the side of the intake manifold right where the turbo was and would make things very tight there. so i decided to use a USDM wrx throttle body which includes a built-in idle control valve in a much more compact configuration. the MS had no problem controlling this valve. i ran into a couple issues when mounting it. first, the throttle cable would need to be at a sharper angle. no problem - i just adapted the mount. second, where the wrx intake manifold throttle body flange had extra space for the idle control valve chamber, the legacy manifold did not. the wrx manifold could not be swapped, as the bolt pattern was completely different! this was pretty simple to adapt for. i recall seeing some people have custom throttle body adapters made, but i chose a very simple route that works. i cut out a piece of sheet metal in the shape of the throttle body, drilled holes in the appropriate places and blocked off the IAC valve chamber (if bolted to the legacy manifold, this chamber would just be open to air and would not admit extra air to the manifold as it should). i then took a dremel with an abrasive cutoff wheel and cut a notch directly into the throttle body bore between the IAC chamber and the bore. pictures will explain better than words.

02-05 USDM WRX exhaust manifold, aftermarket stainless catless uppipe - the uppipe does not clear the legacy engine support crossmember as the car was originally N/A! so two options are available - 1. swap in a turbo legacy crossmember from the early 90's cars. 2. take a cut-off wheel and grinder to it! we took the easy way, #2, and notched the crossmember to fit the uppipe. true, crossmember structural rigidity and durability may have been compromised, but we didnt have time to source a turbo crossmember.

custom fabricated 3" stainless exhaust - WRX exhausts will not fit this car. everything after the downpipe had to be made custom.

02-05 USDM WRX 5-speed transmission, LSD rear end - these swap right in, no problems. i dont remember if any wiring had to be adapted on the transmission, but it would be a very simple thing to do.

04-? USDM STI struts/springs w/ homemade plastic saggy-butt spacers - STI suspension will cause the rear to sit lower and the tires to rub. making spacers from plastic for the top of the struts was a quick, cheap, simple fix.

TIAL blow-off valve - this is my FAVORITE. it sounds awesome, with no hint of rice. i HATE those bov's that sound like a whistle. this is a true man's BOV. it looks good and as long as you have the proper spring installed, it functions just as it should. form and function.

04-? USDM STI 550cc sidefeed injectors & walbro 255 lph fuel pump - these drop right in. important note - make sure that when you are all finished with your build, apply very light boost pressure (5-7 psi) and drive with a fuel pressure gauge connected. you will want to check to make sure your fuel pressure rises on a 1:1 ratio with your boost pressure. if not then you will need to make sure you have an FPR that will work with boost. you DO NOT want a rising rate regulator as this will make tuning very hard and will stress the whole system with the multiplication factor applied to the fuel pressure. the stock legacy FPR worked fine with boost.

Last edited by bmw5002 on Fri May 27, 2011 1:48 pm, edited 2 times in total.

a73camaro wrote:Nice work! Did you use the 6/7 trigger or did you go the STi crank gear route?

thanks! used the 6/7 trigger. we are having issues with it though. we didn't run new wiring for the vr sensors, used the stock shielded wire built into the factory harness. there is some sync loss. we are going to try the jbperf dual vr board which uses a different and more adaptive/tolerant chip to process the signal. hopefully that will clear it up.

cool man thanks. i am going to try the dual vr board since that guy said it worked for him. i already have it, might as well install it. the thing that i am curious about, isnt the cam trigger pattern different between the 6/7 and the 36-2-2-2? That is why I figured that I had to go MS with this motor. I didn't want to swap heads or anything and not many aftermarket ECUs work with the 6/7 pattern. I researched swapping to the 36-2-2-2 setup but I thought that the cam wheels would not fit on this motor.

I replaced my 6-tooth crank gear with a 36-2-2-2 crank gear on a '98 Impreza. Very easy and it used the stock crank VR. And with the 36-2-2-2 crank gear, you don't need a cam signal. One VR signal gets the job done!

a73camaro wrote:And with the 36-2-2-2 crank gear, you don't need a cam signal. One VR signal gets the job done!

Wow! Never realized that. I just figured since the stock ecu used both inputs, the megasquirt would need the same. BUT, i think i see where the difference is. I'm betting that you aren't running sequential injection and coilpacks. Because both of those would be impossible without a cam input, right?

a73camaro wrote:And with the 36-2-2-2 crank gear, you don't need a cam signal. One VR signal gets the job done!

Wow! Never realized that. I just figured since the stock ecu used both inputs, the megasquirt would need the same. BUT, i think i see where the difference is. I'm betting that you aren't running sequential injection and coilpacks. Because both of those would be impossible without a cam input, right?

I am running non-sequential injection and a wasted-spark coil pack. With the 36-2-2-2, the MS can't determine which cylinder to fire, so it fires the 1-2 coil pack when either 1 or 2 is ready for ignition. Here is my set-up

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